Chapters 22 and 19 Flashcards
Adaptation
Inherited characteristic of an organism that enhances its survival and reproduction in a specific environment.
Analogous
Having characteristics that are similar because of convergent evolution, not homology.
Artificial selection
The selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits.
Biogeography
The scientific study of the past and present geographic distributions of species.
Convergent Evolution
The evolution of similar features in independent evolutionary lineages.
Evolutionary tree
A branching diagram that reflects a hypothesis about evolutionary relationships among groups of organisms.
Evolution
Descent with modification; the process by which species accumulate differences from their ancestors as they adapt to different environments over time;
Fossil
A preserved remnant or impression of an organism that lived in the past.
Homologous structures
Structures in different species that are similar in function because of common ancestry.
Homology
Similarity in characteristics resulting from a shared ancestry.
Natural selection
A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.
Paleontology
The scientific study of fossils.
Stratum
(plural, strata) A rock layer formed when new layers of sediment cover older ones and compress them.
Vestigial structure
A feature of an organism that is a historical remnant of a structure that served a function in the organism’s ancestors.
Bacteriophage
A virus that infects bacteria; also called a phage.
Capsid
The protein shell that encloses a viral genome
What kind of virus is HIV?
Retrovirus
Host range
The limited number of species whose cells can be infected by a particular virus.
Lysogenic cycle
A type of phage replicative cycle. the viral genome becomes incorporated into the bacterial host chromosome as a prophage, is replicated along with the chromosome, and does not kill the host.
Lytic cycle
A type of phage replicative cycle resulting in the release of new phages by lysis (and death) of the host cell.
Phage
A virus that infects bacteria; also called a bacteriophage.
Prions
An infectious agent that is a misfolded version of a normal cellular protein.
How do prions increase in number?
converting correctly folded versions of the protein to more prions.
Prophage
A phage genome that has been inserted into a specific site on a bacterial chromosome.
Provirus
A viral genome that is permanently inserted into a host genome.
Retrovirus
An RNA virus that replicates by transcribing its RNA into DNA and then inserting the DNA into a cellular chromosome;
Reverse transcriptase
An enzyme encoded by certain viruses (retroviruses) that uses RNA as a template for DNA synthesis.
Temperate phage
A phage that is capable of replicating by either a lytic or lysogenic cycle.
Vaccine
A harmless variant or derivative of a pathogen that stimulates a host’s immune system to mount defenses against the pathogen.
Viral envelope
A membrane, derived from membranes of the host cell, that cloaks the capsid, which in turn encloses a viral genome.
Virulent phage
A phage that replicates only by a lytic cycle.
Virus
An infectious particle incapable of replicating outside of a cell
What does a virus consist of?
an RNA or DNA genome surrounded by a protein coat (capsid) and, for some viruses, a membranous envelope.
Double stranded DNA virus
Can insert directly into host’s genome (prophage) to be transcribed and translated into the viral proteins
RNA positive strand
Single stranded DNA which can serve as mRNA in protein synthesis
RNA negative strand
single stranded RNA complimentary to what will ultimately be the viral mRNA
What do organisms that share a common ancestry show?
similar nucleotide sequences, greater number of conserved traits, homologies (Structural similarities)
Why are vestigial structures reduced over time?
organisms lose it by accumulation of mutations wherein the organism gains an advantage if its smaller
Allopatric speciation
Populations split into different species due to geographical separation
Sympatric speciation
POpulations not physically separated but speciate via other means
Punctuated equilibrium
variable pace in speciation, large scale changes in short periods
gradualism
small changes spread over long periods of time cause speciation
Why do most populations stay homozygous until some method of segregation is introduced?
gene flow
Point mutation
A single base is removed and replaced by a different base (result: diff amino acid produced)
Frame shift
Frame is shifted one base downstream after a change happens (insertion or deletion)
Double stranded breaks
result of radiation damage, breaks whole double helix
What are some fixes for double stranded breaks?
Transcriptions (use other chromosomes as models), apoptosis
What are slipped mispairings?
Strands of repeated code mispairing, resulting in a loop (often excised)
What is a triplet expansion
Regions of repeated codes growing in length due to copying errors
What are the prezygotic barriers to gene flow?
Ecological (feeding niches), behavioral (mating dances), temporal (breeding seasons), mechanical (breeding structures different)
What happens in inversions resulting in unequal crossing over?
Loop forms in synapsis, one chromosome pairing inverts causing exchange of unequal lengths, the two chromosomes no longer homologs
what is transposition
segments move from one region of a chromosome to another
how does transposition happen?
Enzymes help it along
Whose ideas is the scale of nature based off of (ladder)
Aristotle
Who founded binomial nomenclature?
Linnaeus
What is insertional inactivation?
occurs via transposition, receiving end of the insertion is altered in function or disrupted
What do phylogenic trees show?
Chronology of development of related groups
What do cladograms show?
Degrees of relatedness through common traits
Convergent evolution
Independent evolution of similar features in species unrelated to one another
